1. Field of the Invention
The present invention relates to a flat-proof rim for a pneumatic tyre of a wheel and, more particularly, to such a flat-proof rim in which a plurality of hoofs are moved radially outward only when the tyre is deflated while the wheel is rotated at a high speed.
2. Description of Related Art
Pneumatic tyres are widely used in vehicles, including cars, trucks and even airplanes. Such tyres have an excellent property of absorbing shocks which occur inevitably when the vehicles are traveling on roads or runways after landing. On the other hand, the pneumatic tyres may explode, especially as the vehicles are being driven at a high speed, such as on thruways.
This is because between the tyre and an incorporating rim there is a sealed annular space fill with pressurized air, which does provide the shock-absorbing property. The pressurized air will become hotter, due to the friction between the rotating tyre and the road, resulting in an increased pressure in the space. The higher the speed of the vehicle is, the higher the pressure in the space will be. Then, the tyre explodes when the pressure surpasses a predetermined limit.
For example, a car normally travels on a thruway at a speed up to 60 miles per hour and if one of its tyre explodes and is deflated, the speeding car becomes unstable and possibly out of control whereby a serious accident may occur. It is the same for the trucks and the buses on the thruway, and the landing airplane on the runway, which all involve high speeds.
One of the solutions to the problem is disclosed in a flat-proof rim that includes a ring bushing, made of a material such as nylon, plastic, metal and the like, provided around an outer periphery of a rim body behind a tyre. The ring bushing is normally spaced from the tyre, but supports it if the tyre has been deflated accidentally. The ring bushing, however, is retained in place by the tyre and it will separate from the rim body soon after the tyre explodes.
Another flat-proof rim is also known that includes a plurality of inert hoofs connected in series around an outer periphery of a rim body. Although these hoofs can be into contact with the ground to protect the rim body after the explosion of the tyre, they project from the rim flanges, which makes the tyre difficult to be assembled with and disassembled from the rim body unless special tools are used.
Therefore, it is an objective of the invention to provide a flat-proof rim for a pneumatic tyre of a wheel to mitigate and/or obviate the aforementioned problems.
The object of the present invention is to provide a flat-proof rim in which a plurality of hoofs can be moved radially outward when the tyre is deflated while the wheel is rotated at a high speed.
Another object of the present invention is to provide a flat-proof rim in which a tyre may be assembled therewith and disassembled therefrom easily.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.